(a) Field of the Invention
The present invention relates to a thin film transistor array panel, in particular to a visual inspection means and a method of performing visual inspection in a thin film transistor array panel having a gate driving circuit integrated therein.
(b) Description of the Related Art
A thin film transistor array panel is used as a circuit panel for driving each of pixels independently in a liquid crystal display (LCD) or an organic electroluminescence (EL) display, etc. In the thin film transistor panel, a scan signal wire or a gate wire for transferring a scan signal and an image signal wire or a data wire for transferring an image signal are formed. Also, a thin film transistor connected to the gate wire and the data wire, a pixel electrode connected to the thin film transistor, a gate insulating layer for covering and insulating the gate wire and a passivation layer for covering and for insulating the thin film transistor and the data wire are formed therein. The thin film transistor comprises a semiconductor layer fanning a channel together with a gate electrode that is a part of the gate wire, a source electrode and a drain electrode that is a part of the data wire, the gate insulating layer and the passivation layer. The thin film transistor is a switching element that transmits the image signal transmitted through the data wire to the pixel electrode depending on the scan signal transmitted through the gate wire.
An LCD is a representative of display devices using such a thin film transistor panel, and especially a middle-small type LCD, such as a reflection type or semi-transmittance type mostly, employs a COG (chip on glass) type. In this case, visual inspection (VI) or gross test (GT) is done before a COG IC mounting process so as to save expensive COG ICs, polarizers and a compensating film and to increase the yield. It is difficult to apply GT to a practical process since the test requires an expensive equipment and furthermore a long processing time. In addition, a currently available VI is performed after forming a wire for inspection to connect gate lines and data lines between the COG terminals or to its opposite side to perform the VI, then a diamond-cutting is done together with a panel or a laser-cutting is done to divide the wire for inspection. In this case, in such a cutting process, pollutant particles are generated or the wire is corroded through a cut side thereof, and thereby degrading the reliability.
In the meanwhile, TFT panels can be manufactured by a method in which a driving integrated circuit is directly formed on the thin film transistor, either partially or as a whole. As such example, there are a poly silicon thin film transistor panel (Poly TFT Panel) and an amorphous driving integrated circuit panel (a-si IC Panel). In the method of directly forming the driving IC on the TFT panel as a whole, GT can be performed by the TFT itself. However, the method of directly forming only a portion of the driving IC on the TFT panel needs an expensive equipment to perform GT.
Furthermore, it is hard to employ a laser-cutting after inspection since the driving IC formed on the TFT works as impediments on laser-cutting and, due to forming the TFT panel and a color filter panel in a same size, a space for laser-cutting is not easy to obtain.